Percutaneous interventional procedures to treat occlusive vascular disease, such as angioplasty, atherectomy, and stenting, often dislodge material from the vessel walls. This dislodged material, known as emboli, enters the bloodstream and may be large enough to occlude smaller downstream vessels, potentially blocking blood flow to tissue. The resulting ischemia poses a serious threat to the health or life of a patient if the blockage occurs in critical tissue, such as the heart, lungs, or brain.
The deployment of stents and stent-grafts to treat vascular disease, such as aneurysms, involves the introduction of foreign objects into the bloodstream, and also may result in the formation of clots or release of emboli. Such particulate matter, if released into the bloodstream, also may cause infarction or stroke.
Numerous blood filters have been designed to capture material liberated from vessel walls during the treatment of vascular disease. Such treatment procedures, such as angioplasty, typically involve transluminally inserting an interventional device, such as an angioplasty catheter, to the treatment site along a guidewire. During a typical interventional angioplasty treatment procedure, the balloon of the angioplasty catheter is inflated within the vessel at least once but often more than once. First a pre-dilatation angioplasty catheter is inflated against the vessel to pre-dilate it. Next a stent delivery angioplasty catheter is inflated to deploy the stent. Finally a post-dilation angioplasty catheter is inflated to properly seat the stent against the vessel. Each of the inflations and manipulations of the interventional devices often liberate emboli from the vessel walls. The emboli enters the bloodstream and flows into a vascular filter, where it remains for the duration of the treatment procedure.
Is has been postulated that a vascular filter may become occluded with emboli during a transluminal diagnostic or therapeutic procedure, thus occluding flow of blood through the filter. Additional emboli, generated proximal to the vascular filter by the angioplasty catheter, may then be unable to flow downstream and into the vascular filter. When the vascular filter is collapsed for retrieval, the restored flow of blood through the vessel may carry those additional emboli downstream past the collapsed filter, potentially jeopardizing the patient's health.
An additional disadvantage postulated to occur when retrieving an emboli-ladened vascular filter is that the vascular filter may become entangled with a stent disposed within the patient's vessel. If, for example, a stent has been deployed, the vascular filter may inadvertently engage a stent strut, preventing further advancement of the vascular filter within the vessel, or even possibly causing vessel dissection.
Also, emboli may temporarily adhere to stents disposed within a patient's vessel. When blood flow is subsequently restored, the emboli may re-enter the bloodstream and cause infarction or stroke.
In view of the foregoing, it would be desirable to provide improved apparatus and methods for aspirating emboli from a blood vessel in which a vascular filter is used in conjunction with a transluminal diagnostic or therapeutic procedure and/or in which a stent is deployed.